v2.4.0.6
Available-For-Sale Securities (Summary Of Available-For-Sale Debt Securities In A Continuous Unrealized Loss Position Deemed Not To Be Other-Than-Temporarily Impaired) (Details) (USD $)
In Thousands, unless otherwise specified
Mar. 31, 2012
Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]    
Less than 12 months, Gross Unrealized Losses $ 0 $ 30,528
Less than 12 months, Estimated Fair Value 0 1,269,712
12 months or greater, Gross Unrealized Losses 3,332 4,548
12 months or greater, Estimated Fair Value 48,168 46,952
Total, Gross Unrealized Losses 3,332 35,076
Total, Estimated Fair Value 48,168 1,316,664
Certificates of Deposit [Member]
    
Schedule of Available-for-sale Securities [Line Items]    
Less than 12 months, Gross Unrealized Losses 0 18
Less than 12 months, Estimated Fair Value 0 1,019,982
12 months or greater, Gross Unrealized Losses 0 0
12 months or greater, Estimated Fair Value 0 0
Total, Gross Unrealized Losses 0 18
Total, Estimated Fair Value 0 1,019,982
Non-U.S. Government Securities [Member]
    
Schedule of Available-for-sale Securities [Line Items]    
Less than 12 months, Gross Unrealized Losses 0 30,505
Less than 12 months, Estimated Fair Value 0 24,741
12 months or greater, Gross Unrealized Losses 0 0
12 months or greater, Estimated Fair Value 0 0
Total, Gross Unrealized Losses 0 30,505
Total, Estimated Fair Value 0 24,741
Corporate Debt Securities [Member]
    
Schedule of Available-for-sale Securities [Line Items]    
Less than 12 months, Gross Unrealized Losses 0 5
Less than 12 months, Estimated Fair Value 0 224,989
12 months or greater, Gross Unrealized Losses 0 0
12 months or greater, Estimated Fair Value 0 0
Total, Gross Unrealized Losses 0 5
Total, Estimated Fair Value 0 224,989
Student Loan-Backed Securities [Member]
    
Schedule of Available-for-sale Securities [Line Items]    
Less than 12 months, Gross Unrealized Losses 0 0
Less than 12 months, Estimated Fair Value 0 0
12 months or greater, Gross Unrealized Losses 3,332 4,548
12 months or greater, Estimated Fair Value 48,168 46,952
Total, Gross Unrealized Losses 3,332 4,548
Total, Estimated Fair Value $ 48,168 $ 46,952